Polysiloxanes are known to give interesting properties as resins and coatings. True advancements in the state-of-the-art for protective coatings require substantial improvements in weathering (primarily ultraviolet resistance), heat resistance, chemical resistance and corrosion control. Polysiloxane chemistry offers the potential for providing many of these advancements. Polysiloxane is defined as a polymer consisting of repeating silicon-oxygen atoms in the backbone that imparts several advantages over previously used carbon-based polymer binders; one of these advantages being an enhanced chemical and thermal resistance due to the silicon-oxygen bond. Polysiloxane's polymer linkage is also transparent to ultraviolet light making it resistant to ultraviolet degradation. Finally, polysiloxane is not combustible and is resistant to a wide range of chemicals and solvents, including acids.
Functional polysiloxanes have been described. U.S. Pat. No. 4,413,104 to Wacker describes a process for preparing organo-functional polysiloxanes such as amino-functional polysiloxanes and copolymers thereof. These organo-functional polysiloxanes possess a Si—C bond between the polymeric polysiloxane backbone and the functional linking arm. WO 01/09261 describes coating compositions comprising as component functional polysiloxanes comprising reactive functional groups.
It is an object of the present invention to provide new organo-functional polysiloxanes, which can be prepared with a simple method. It is another object to introduce functional groups on a polysiloxane backbone, which are reactive with amine radicals. It is yet another object of the present invention to provide new coating compositions comprising said organo-functional polysiloxanes with improved hardness development without impairing chemical, mechanical and weathering resistance.